/Engine/Plugins/BlueprintFileUtils/Source/BlueprintFileUtils/Public/BlueprintFileUtilsBPLibrary.h
Get the users directory. Platform specific (usually something like MyDocuments or the users home directory
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintPure, Category="FileUtils") static [FString](API\Runtime\Core\Containers\FString) GetUserDirectory()